Hand tools have been around for years in many forms. To increase the usefulness of some hand tools, features were developed to allow the tools to adjust to varying workpiece sizes. That is, instead of changing to a bigger or smaller tool, a single tool could be adjusted to accommodate a larger or smaller sized workpiece, saving on time and the number of tools required for any given job.
One such feature developed to make tools adjustable is the use of multiple pivoting centers for jawed hand tools, such as pliers. A pivot attached to one half of the tool is capable of freely sliding between any number of centers connected by slots. Typically, three pivoting centers are used for engaging a small, medium and large workpiece.
U.S. Pat. No. 1,867,912 to Evey discloses one way for providing a path to connect each of the three pivot centers. The centers are connected by adjoined slots/paths such that each pivot center is at the end of a slot. However, manipulation of the tool halves to move irregularly between pivot centers is unnecessarily complex for the user, and may require visual confirmation of proper pivot centering.
A more popular alternative adjustment design is illustrated in U.S. Pat. No. 1,520,613 to Thim. The single-slot or path having multiple (e.g., three) pivot centers at regular points just off the path requires less complex manipulation to move between centers (i.e., pin travel along the slot is substantially linear, but “locking” into a pivot center still requires a slight transverse movement of the pivot pin). However, movement and centering may still be overly complex and require visual confirmation.
The present instrument in its various embodiments provides a solution to these and other problems in the relevant field.